I managed to save 1 second from the 12:59.93 TAS thanks to so new optimizations by Himmdawg! He found a new strat in Zulag 1 where you can do the zulag without grenades!
Wasn't the last TAS a 12:59.96? Also, I believe this is a little less than a second. If I'm correct, this is a 0.73 second improvement.